1. Field of the Invention
The present invention relates to an image reader and a light guide used for an image reader. The present invention further relates to a method of making a light guide.
2. Description of the Related Art
An example of conventional image reader is disclosed in JP-A-2004-266313. The conventional image reader is designed to obtain proper image data by enhancing the irradiation efficiency in irradiating an object to be read with linear light.
Examples of object to be read include securities such as a check and bills as well as documents printed on general-purpose recording sheets. Bills may have a wrinkle or a crease on the surface. In reading the image of such a bill using the conventional image reader, a shade may be formed on the surface of the bill irradiated with linear light. This shade appears as a dark portion in the image obtained, which is not desirable. Thus, to solve this problem and achieve proper image reading, the conventional image reader still has room for improvement.
Further, for a conventional image reader, improvement in a light guide to enable uniform linear light emission is demanded. Moreover, to prevent the deterioration of resolution due to out-of-focus, a structure which enables precise and easy fixing of an optical part such as a lens unit to a predetermined position is demanded.